Journal of Experimental and Theoretical Physics Letters
Boltzmann spectral distribution or “infrared catastrophe” in the resonance radiation of a gas
Yu. K. Zemtsov, A. Yu. Sechin, A. N. Starostin, Alexei G. Leonov, Dmitriy I. Chekhov
Abstract
The purely thermal infrared emission spectra of a resonance medium (sodium vapor) are investigated experimentally. It is shown that the emission intensity in the 2–3 μm range at temperatures of 600–1200 K is several orders of magnitude higher than the intensity obtained from the standard theory of resonance radiation transfer. This phenomenon can be conventionally termed an “infrared catastrophe.” The form of the recorded spectra and the absolute intensity of the emission in both the infrared and visible regions of the spectrum are in agreement with the theory developed by Yu. L. Zemtsov and A. M. Starostin, Zh. Éksp. Teor. Fiz. 103 , 345 (1993) [JETP 76 , 186 (1993)], in which the Boltzmann spectral distribution of the population of the resonance level is proportional to exp(−ħω/ T ).